Process for the manufacture of permanganates



, Improved Process for UNITED (STATES PATENT OFFICE.

HENRY enemas mnxms AND noon woomna, or LONDON, ENGLAND.

rnocnss roa rim. nmumc'ruar. or

PERMANGANATES.

1,377,48'5. 1V0 Drawing. Application filed February 8,

To all whom it may concern:

Be it known that we, HENRY CHAnLns JENKINS, a subject of the King of Great Britain, residingat 815/7 Salisbury House, London, England, and UGH Woommn, a subject of the Kin of Great Britain, residing at 810/1, Sa isbury House, London, England, have invented a new and useful the Manufacture of Permanganates, of which the following is a specification.

This invention relates to an improved 7 process for the manufacture of potassium process,

permanganate. I

According to this invention, sodium manganate and mangan'te are made by a fusion the main primary materials employed (other than those derived from the process) beingmanganese dioxid and caustic soda, magnanate being then transformed by electrolysis to permanganate, which is then separated from the liquor, largely by precipitation, of potash or a potassium salt.

The method of procedure includes (1) a lengthy and gentle fusion processin whic a large excess of sodium hydroxid 1s employed preferably the presence of a small quantity of potassium hydroxid, (2) a dissolving of the fused mass in a liquor which is derived from the electrolytic process or in water, (3) separation of a solution containing sodium (and potassium) manganateand other soluble materials, from the mud (i.e.,Mn,,O mud present), said mud being thereafter added to the primary manganese dioxid, (4) the known electrolytic process manganate,

of convertin sodium manganate into per- %5) precipitation of potassium permanganate and employment of the residual solution as a solvent of the fused mato the primary mananese dioxid and (6) return of the-liquor rom which the permanganate recrystallized for admixture with the primary material employed.

The invention may be carried out as follows :-m 7 Stage 1.-The production of a manganate and some mangamite mamly of soda.

To 120 lbs. manganese dioxid (pyrolusite), which may be partly replaced by the mixture of lower oxids of manganese mud roduced in the process, 40 gallons of 40% soda lye (NaOH solution) and the equiva- Speciflcation of Letters Patent.

. at about 250 to 300 7 recrystallization and no special for example by the addition Patented May 10, 1921.

1919. Serial No. 274,701.

lent of 12 lbs. of dry manganate residuals (this may be efiecte by adding the calculated equivalent of the lye of the liquor obtained by evaporation of the liquor from which a permanganate has been precipitated) are evaporated to dryness while stir ring preferably in an open iron pan and when dry maintainedcfor about six hours The temperature of the mixture is now brought to a very dull red and maintained in fusion at the dull red heat, and freely exposed to the atmosphere or in as needed. The total time per charge is from twelve to twenty-four hours.

The presence of some potassium compounds is desirable, since their presence enables the manganese to be more highly oxidized than when the alkali is entirely soda; the potash is derived from the residues after potash is necessary.

In some cases as when manganese mud is used, or according to the commercial manganese dioxid employed or whenlower manganese oxids', are present in the charge, it may be necessary to assist oxidation by the addition of chlorate of soda, or the oxidation may be entirely effected by its addition in which case to the mixture above set out 22 lbs. and upward of sodium chlorate are added. l

By this treatment the manganese is oxidized from MnO up to an oxygen ratio approximating to that of Mn O Stage 2.

The melt is as it cools broken up coarsely and either dissolved cold in a iiquor containing permanganate and produced as hereinafterdescribed, or solution is effected in 80 gallons of water at about 20 C.

The solution is allowed to settle for about 48hours and then filtered. The filtration should be carried out in a manner to thoroughly remove all traces of the mud as even small quantities of the mud which is excessively fine have a prejudicial effect on subsequent operations and lead to serious loss of permanganate. The material employed for the filtration should have fine pores and should be one not injured by the liquor; biscuit porcelain has been found to be very suitable. The clear green liquor obtained should lent on titration to about 6 grams permanaddition of contain sodium manganate equivaganate per 100 c.

. tion of a states itself during the slow cooling :llquor as first crystals.-

and its specific gravity 18 about 1.25.

Stage 3.-Tiw electrolysis of sodium mamganate.

The electrolysis to permanganate may take place inrany usual manner, but preferably we'emp'loly nickel anodes and iron cathodes. The vo t uor requires a out 150 ga lon, and we find 120 suitable temperature.

During electroylsis the green manganate is converted into the red permanganate until titration indicates 7% grams of permaniganate per 100 'c. c. When the operation is ampere hours per to 30 Cato be a nished and the'cells discharged.

Stage 4.-Tramsfmmt ion of sodium per- Wm'nganatev into potassium permanganate.

This is effected by adding a 'stron solution of about 0.5 to 0.6 lb. per ga on of potassium chlorid or the equivalent of caronate,- hydroxid or other potassium salt. The whole is well stirred and allowedto settle for from three to four days at a temperature of about 10 C. or as near to freezing as can conveniently be secured. Potassium permanganate separates out and precipithat-folthe stock These are collected and drained and recrystallizedin the usual manner. 4

The liquid is now again filtered through biscuit porcelain totake out any manganese lows and is recovered with some 0 reclpitates or any fine crystals and is (if ree rom carbonate) evaporated to half its bulk when it is ready to be used again in a further fusion dissolve the melt as herein before described and its soda and manganate utilized. Excess of chlorid is eliminated at this stage by allowing the lye to cool and settle and then decanting it. Any alkaline corbonate can be likewise separated and' the alkali made available again well known manner.

at we claim is 1. An improved process for the manufacture of potassium permanganate, which consists in fusing together manganese dioxid with an excess of an alkaline sodium compound at a dull red heat with the employment of an oxidizing agent, dissolving the melt, completely separatin the solution from the manganese mud, e ectrolyzing the liquor to produce permanganate, forming and separating potassium permanganate from the-permanganate liquor by the addipotassium compound, reusin the sodium compounds in the remaining liquor in the first step of the process.

2. An improved process for the manufacture of potassium permanganate which a e may be 4 volts and the by filtration, duce permanganate, the

p the permanganate has been rocess or ma be used to in caustic form in the consists in fusing together a mixture comprising manganese dioxid, a potassium salt and an excess of caustic soda at a dull red heat with the employment of an oxidizing agent, dissolving the melt, separating the ,the permanganate into' cess of an alkaline sodium compound at a dull red heat, dissolving the melt, separating the solution from the manganese mud and electrolyzing the liquor to produce permanganate.

4. An improved process for the manufacture of potassium permanganate which consists in fusing together manganese dioxid with an excess of a sodium compound at'a dull red heat with the employment of an oxidizing agent, dissolving the melt, separating the solution from the manganese mud electrolyzing the liquor to prosium permanganate from the permanganate liquor by the addition of a potassium compound and utilizing the liquor from which separated in the process. a

5. An improved process for the manufacture o potassium permanganate which consists in fusing together manganese dioxid with an excess of an alkaline sodium compound at a dull red heat with the employment of an oxidizing agent, dissolving the melt, filtering the liquor obtained through 2 material havinga suflicient fineness of pore to completely remove all traces of man anese mud from the solution, electrolyzing the liquor to produce permanganate, separating the potassium'permanganate fromthebiscuit porcelain. 7. An improved process for the manufacture of potassium permanganate which consists in fusing togeth with an excess of an pound at a dull ment of an oxid melt, separating er manganese dioxid alkaline sodium comred heat with the employizing agent, dissolving the the solution from the manseparating potaspermanganate liquor ganese mud, electrolyzing the liquor to produce permanganate, forming and separating potassium permanganate from the permanganate liquor by t 1e addition of potassium chlorid, concentrating the liquor so obtained, separating the chlorids so precipitated and utilizing the sodium containing residues in the process.

8. An improved process for the manufacture of potassium permanganate, which consists in fusing together manganese dioxid with an excess of an alkaline sodium compound at a dull red heat with the employment of an oxidizing agent, dissolving the melt, separating the solution from the manganese mud, electrolyzing the liquor to produce permanganate, separating the potassium permanganate and utilizing the liquor from which the permanganate has been separated in the process.

9. An improved process for the manufacture of potassium permanganate, which con-v sists in fusing together manganese dioxid with an excess of an alkaline sodium compound at a dull red heat, with the employment of an oxidizing agent, dissolvingthe melt, filtering the liquor obtained through biscuit porcelain, electrolyzing the llquor to produce permanganate, separating the potas'. sium permanganate from the permanganate liquor by the addition of a potassium compound and utilizing the liquor from which the permanganate has been separated in the rocess.

10. In the manufacture of permanganate by fusing together a manganese oxid with an alkaline sodium compound while allowing oxidation, dissolving the melt, separating insolubles from the resultant solution and oxidizing to form permanganate, the herein described improvement which comprises completely separating the insolubles from the liquor produced by dissolving the melt,by filtering said liquor through a porcelain filter.

11. An improved process for the manufacture of potassium permanganate which consists in electrolyzing sodium manganate to produce permanganate, forming and separating potassium permanganate from the permanganate liquors by the addition of a potassium compound, and reusing the sodium compounds for the manufacture of sodium manganate.

In testimony that we claim the foregoing as our invention we have signed our names this seventh day of January, 1919.

HENRY CHARLES JENKINS. HUGH WOOLNER. 

